This proposal will examine the hypothesis that Parkinson's disease (PD) subjects have increased oxidative stress both systemically and in the CNS. PD and control subjects will have salicylate loading with oral aspirin, as a convenient method to assay levels of reactive oxygen species (ROS). Cybrid cells will be made from each subject to compare in vivo with in vitro ROS production. ROS production in serum and csf will be compared before and during L-DOPA infusion.